Using natural light to assist illumination is one of the methods for saving the power consumption of light illumination, but the natural light is limited by different conditions including the interior layout of a building, such as a dark basement of a building or a room blocked by walls. Therefore, if natural light can be collected and conveyed to an indoor environment or any other place requiring illumination, the utilization of natural light will be improved.
In a light energy conveyance related prior art, U.S. Pat. No. 4,246,477 has disclosed a system capable of collecting sunlight, and conveying and distributing the light energy of the sunlight into a building through a conveyance channel. In the conveyance channel, light energy is conveyed by using focusing lenses to receive the light energy, and then a reflective mirror installed at a specific position of the conveyance channel to reflect the light energy to a specific position to provide illumination.
As disclosed in U.S. Pat. No. 6,691,701 and European Patent Publication No. EP2385297 A1, a sunlight collecting system collects sunlight by a primary reflector and directs the sunlight to a secondary reflector, and then uses an adjustable planar reflector to direct the light energy into a building for illumination. Similar literatures such as “The most innovative building integrated daylighting system by Sunportal, brochure received on Sep. 22, 2011” discloses the similar principle.
Although the aforementioned prior arts can convey the external light energy into a building, the major problem resides on the constant loss or attenuation of the collected light energy along the conveyance channel in the conveyance process. For example, a single lens on the conveyance channel reflects approximately 8% of the light for illumination. After 100% of the light energy passes through the front lens, and then through the second to tenth lenses, the conveyed energy is attenuated sequentially to approximately 84%, 77%, . . . 43% of the original energy respectively, and the light energy passing through each lens for illumination becomes less and less. In other words, the longer the distance of conveying light energy on the conveyance channel, the less the energy, and the lower the illumination capability.
The aforementioned loss and attenuation of light energy occurred in the conveyance process is an inevitable physical phenomenon, so that the technical content of U.S. Pat. No. 4,246,477 has disclosed and provided an artificial lighting system to overcome the problems. Theoretically, the light energy emitted by the artificial light source can be controlled precisely, but when the artificial light source is controlled, it is necessary to cope with the attenuation of the illumination along the conveyance channel in order to maintain the same brightness of the illumination after the natural light released from front and rear ends of the conveyance channel is added to the artificial light source. Therefore, the construction and control of the whole illumination system will become more complicated, and the implementation will become more difficult.